Preheat your oven to 350°F (175°C). Grease a 9x13 inch baking pan and line it with parchment paper, allowing some excess to hang over the edges for easy removal later on.
In a medium saucepan, melt the unsalted butter over medium heat. Once fully melted, remove it from the heat and stir in both the granulated sugar and packed brown sugar until well combined. Let the mixture cool for about 5 minutes.
Incorporate the eggs into the slightly cooled butter-sugar mixture, one at a time, mixing thoroughly after each addition until smooth. Stir in the vanilla extract until evenly blended.
In a separate mixing bowl, whisk together the all-purpose flour, unsweetened cocoa powder, and sea salt.
Gradually fold the dry ingredients into the wet mixture, mixing gently until just combined. Be careful not to overmix, as this will help keep the brownies tender.
Gently fold in the semi-sweet chocolate chips and chopped pecans until they are evenly distributed throughout the thick brownie batter.
Pour half of the brownie batter into the prepared baking pan, spreading it out evenly. Drizzle half of the caramel sauce over the brownie layer.
Carefully spread the remaining brownie batter over the caramel layer, then drizzle the rest of the caramel sauce on top. Using a knife or a skewer, gently swirl the caramel into the brownie batter to create a marbled effect.
Place the pan in the preheated oven and bake for 25-30 minutes. The brownies are done when a toothpick inserted into the center comes out with a few moist crumbs attached, but not wet batter. Do not overbake to ensure they remain fudgy.
Once baked, allow the brownies to cool in the pan for at least 30 minutes before carefully lifting them out using the parchment paper. Cut into squares and savor every gooey, chocolatey bite!
Notes
Serve warm with vanilla ice cream and extra caramel sauce.